eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Atrial Flutter

Author: M Silvana Horenstein, MD, Consultant, Pediatric and Fetal Cardiac Diagnostic, Diagnostico Gineco-Obstetrico, PC; Associate Medical Director, Legacy Department, Best Doctors, Inc
Coauthor(s): Robert Murray Hamilton, MD, MSc, FRCPC, Section Head, Electrophysiology, Director, High-Risk Hereditary Heart Conditions Clinic, Labatt Family Heart Centre; Professor, Department of Pediatrics, Associate Scientist, Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, University of Toronto, Canada
Contributor Information and Disclosures

Updated: Sep 19, 2008

Introduction

Background

Atrial flutter is an electrocardiographic descriptor used both specifically and nonspecifically to describe various atrial tachycardias. The term was originally applied to adults with regular atrial depolarizations at a rate of 260-340 beats per minute (bpm). Historically, the diagnosis of atrial flutter was restricted to those patients whose surface ECG revealed the classic appearance of "flutter waves." This sharp demarcation is used less frequently in the current era.

In the fetus, atrial flutter is defined as a rapid regular atrial rate of 300-600 bpm accompanied by variable degrees of atrioventricular (AV) conduction block, resulting in slower ventricular rates.

When the atrial rate is such, normal AV nodes usually have a physiologic second-degree block, with a resultant 2:1 conduction ratio. In individuals with AV nodal disease or increased vagal tone, or when certain drugs are used, higher degrees of AV block may develop. In individuals with accessory AV nodal pathways, a 1:1 conduction ratio may occur, with resultant ventricular rates of 260-340 bpm, which can cause sudden death. A 1:1 conduction ratio may also occur when the atrial rate is relatively slow (eg, <340 bpm) during atrial flutter or when physiologic processes facilitate AV nodal conduction such that a rapid ventricular response can still result in sudden death.

Atrial flutter is infrequent in children without congenital heart disease. Patients who have undergone Mustard, Senning, or Fontan procedures are more prone to develop this arrhythmia because of atrial scars from surgery and right atrial enlargement, such as is found after the classic Fontan operation.

Similarly, patients who have undergone surgical repair of atrial septal defect, total anomalous pulmonary venous connection, and tetralogy of Fallot may later develop atrial flutter. Individuals with muscular dystrophies such as Emery-Dreifuss and myotonic dystrophy may also develop atrial flutter, as well as those with dilated, restrictive, and hypertrophic cardiomyopathies.

Pathophysiology

The pathophysiology of atrial flutter is a reentrant arrhythmia circuit confined to the atrial chambers. Such a circuit may be macroscopic and, therefore, amenable to mapping by techniques using standard electrophysiologic catheters or it may be microscopic and amenable to mapping only in the research laboratory using fine electrode arrays.

As a rule, atrial flutter originates in the right atrium, whereas atrial fibrillation, which is more frequent in adults, originates in the left atrium.

A flutter circuit typically surrounds an anatomical or functional barrier and includes a zone of slow conduction (or conduction over an extended circuit) and an area of unidirectional block, as required for reentry of all types. Frequently, a premature beat blocks one limb of the circuit and is sufficiently delayed in the other limb (while traversing around the anatomical or functional barrier) to allow for recovery from refractoriness in the first limb.

The reentrant circuits that occur in children with atrial flutter after congenital heart disease surgery are typically more variable than those in adults, who generally have atrial flutter confined to the tricuspid valve–coronary sinus isthmus (or isthmus-dependent flutter). The difference in children with congenital heart disease is believed to be secondary to abnormal atrial tissue that has been subject to chronic cyanosis, inflammation secondary to surgery, scarring, and increased wall stress in cases of enlarged atria. Such circuits may encircle anatomical barriers such as atriotomy scars or surgical anastomoses, and they may use areas of slow conduction along baffle limbs and other sites of injury in addition to the tricuspid valve–coronary sinus isthmus.

Sinus node dysfunction with bradycardia is generally present in many of these patients years after surgery. This is a contributing factor for development and maintenance of atrial flutter.

Frequency

United States

According to one study, 57% of patients with double inlet left ventricle who undergo the Fontan operation may be expected to present with atrial flutter or fibrillation 20 years after surgery.¹

International

• In one review, atrial flutter accounted for 26.2% of all cases of fetal tachyarrhythmias, and supraventricular tachycardia (SVT) accounted for 73.2%.²
• In an earlier population study of 3383 newborns by Southall and colleagues, only 1 newborn had atrial flutter.³ This likely underestimated the incidence of atrial flutter in utero because spontaneous conversion often occurs during birth and subsequent recurrence is uncommon.
• A long-term follow-up study into adulthood of patients undergoing the Mustard or Senning procedure for correction of D-transposition of the great vessels demonstrated SVT in 48%, of which atrial flutter was the most common type (73%).
• The mean annual incidence of new dysrhythmias (predominantly atrial flutter) after the Fontan operation is 5%.
• Arrhythmias accounted for 12.7% of pediatric cardiology consultations in a major pediatric academic medical center, of which atrial flutter was the second most common type.

Mortality/Morbidity

In patients who present with atrial flutter, morbidity and mortality largely depend on their age at presentation, cardiac anatomy (normal anatomy vs congenital heart disease), integrity and anatomy of the myocardial conduction system (normal sinus node vs sinus node dysfunction; AV block vs normal AV node, with or without accessory pathways), ventricular function, and availability of prompt recognition of the arrhythmia by the physician and initiation of adequate therapy.

• The fetus with atrial flutter may have significant morbidity and be at risk for mortality. According to one review, hydrops fetalis developed in as many as 40% of fetuses with atrial flutter. The mortality rate in these fetuses was 8%.²
• Mortality in newborns with atrial flutter is uncommon. Most patients remain in sinus rhythm following their initial conversion, and the need for antiarrhythmic prophylaxis in these patients during infancy is debated.
• In patients with postoperative atrial flutter that develops late following repair of congenital heart disease, the severity of presentation depends on the atrial flutter rate, conduction ratio, and presence of ventricular dysfunction. In patients who have undergone the Mustard procedure, Holter recordings incidentally capturing episodes of sudden fatality confirm that rapidly conducted atrial flutter is the dysrhythmia most frequently responsible for these fatalities. In contrast, patients who have undergone the Fontan procedure rarely die suddenly but frequently present with symptomatic atrial flutter. This may be caused by a relatively slower atrial flutter rate, a higher degree of AV conduction block, or both.
• When women with heart disease and arrhythmias reach childbearing age, arrhythmias can recur during pregnancy, significantly increasing the risk for the mother and fetus.
• Prolonged episodes of atrial flutter in asymptomatic or mildly symptomatic patients may be associated with development of atrial thrombi and although rarely in the congenital heart disease population, the possibility of thromboembolic events.

Sex

Following atrial septal defect repair, the prevalence of atrial flutter is higher in females (70.7%) than in males.

Age

As implied above, the prevalence and outcome of atrial flutter depend on the patient's age at presentation and associated causes.

• The fetus with atrial flutter may have associated mortality and risk for morbidity, as stated above. Because atrial flutter occurs mainly during the third trimester, the atrium is believed to reach a critical mass to support an intra-atrial macroreentry circuit at about 27-30 weeks' gestation.
• Atrial flutter in newborns requires immediate treatment, but this is unlikely to recur. Atrial flutter in children usually relates to repairs of congenital heart disease.
• Patients with Fontan repairs present with flutter either as children or as adults.
• Patients with repaired tetralogy of Fallot tend to present with atrial flutter as young adults.
• Because the Mustard and Senning procedures are now rarely performed, the cohort of patients with this substrate typically consists of older adolescents and adults.
• One study reported that the recurrence rate of atrial flutter and fibrillation in women with preexisting cardiac rhythm disorders during pregnancy was the highest of all the studied arrhythmias, reaching 52%.⁴

Clinical

History

Historical aspects of atrial flutter are important in designing a treatment plan, particularly in the setting of repaired congenital heart disease.

• The flutter may be perceived as a regular or irregular palpitation, the latter suggesting variable atrioventricular (AV) conduction.
  • The flutter may be associated with syncope, severe presyncope, or chest pain, suggesting either periods of 1:1 conduction ratio or associated ventricular dysfunction. Characterizing a history of previous self-terminating episodes is important.
  • Rare minimally symptomatic self-terminating episodes of atrial flutter are likely to require less treatment.
• The presence of associated sinus node disease with episodes of sinus bradycardia may provide an indication for pacemaker therapy, which also adds to the antiarrhythmic medical options for atrial flutter.
• Understanding the specific anatomy and surgical repair for each patient is important. Certain types of repair are more commonly associated with late atrial flutter than others.
  • In Fontan-type operations, atriopulmonary connections are associated with a risk of atrial flutter that is 2.5-fold higher than the total cavopulmonary connection.
  • Extracardiac Fontan repairs may have an even lower frequency of atrial flutter.
  • The type of repair may influence the technical approach to electrophysiological study, pacemaker placement, potential radiofrequency ablation therapy, or potential Fontan surgical revision. For example, patients who have the classic Fontan operation are amenable to ablation attempts of the atrial flutter in the electrophysiology laboratory because the right atrium can be approached via the inferior and/or superior vena cava. In addition, endocardial pacemaker leads can be inserted if the patient has sinus node dysfunction. However, patients who have an extracardiac Fontan repair in which the right atrium has been bypassed with a baffle require open-heart surgery if ablation is contemplated, which is performed at the time of their Fontan revision. In addition, only epicardial pacemaker leads can be placed in these patients.
• Several studies have shown that atrial flutter in the early postoperative period in patients who have undergone the Fontan operation predicts both early operative mortality and recurrence of the arrhythmia.
• In patients with congenital heart disease who have undergone surgery, episodes of atrial flutter have been shown to increase in frequency over time.

Physical

Physical examination in patients with atrial flutter should complement the history discussed above.

• The evaluation should assess the likely conduction ratio and rate of flutter and assess for signs of associated ventricular dysfunction or heart failure.
  • Depending on the ventricular rate and the individual's tolerance to that rate, symptoms may range from palpitations, dyspnea, presyncope, or syncope to sudden death.
  • If the ventricular response is rapid, atrial flutter may cause significant morbidity secondary to hemodynamic deterioration due to low cardiac output.
  • If the ventricular response is slow enough to permit a sustained arrhythmia, atrial thrombosis with consequent thromboembolism may result.
  • In patients who have undergone surgery for congenital heart disease, new onset of atrial arrhythmias such as atrial flutter may indicate elevated right atrial pressure and, thus, the need for surgery (eg, conduit obstruction in a patient with a Rastelli-type surgery).
• In patients who have undergone the Fontan, Mustard, or Senning operation, the presence of superficial venous collateralization suggests associated obstruction of major venous pathways, which may interfere with evaluation and management.

Causes

• Most fetuses and neonates with atrial flutter have structurally normal hearts. However, when atrial flutter is detected in a fetus, structural cardiac anomalies such as Ebstein anomaly of the tricuspid valve and AV septal defects should be ruled out because of a higher incidence of these defects.
• Some newborns and young children have associated conditions or anomalies that may predispose them to atrial flutter.
  • Atrial septal aneurysms appear to be associated with sustained atrial arrhythmias in newborns.
  • Restrictive cardiomyopathies are also associated with refractory atrial flutter.
  • In Costello syndrome, the dysmorphic appearance is also associated with a dysrhythmia characterized as chaotic atrial tachycardia, and this dysrhythmia may include long episodes of atrial flutter.
• Atrial flutter is not uncommon in the immediate postoperative period after congenital heart surgery.
• Surgery-induced inflammation of the pericardium, scarring, and volume overload may trigger atrial flutter.
• Case reports have linked atrial flutter to ingestion of herbal medicines and certain foods. These episodes had not recurred after avoidance of the triggers.
• Atrial flutter and atrial fibrillation have been related to obesity, alcohol consumption, and hyperthyroidism.
• One study reported that diabetes mellitus is a strong independent risk factor for development of atrial flutter and atrial fibrillation in adults.⁵

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